What is a moth doing under water? Ecology of aquatic and semi-aquatic Lepidoptera

This paper reviews the current knowledge on the ecology of aquatic and semi-aquatic moths, and discusses possible pre-adaptations of the moths to the aquatic environment. It also highlights major gaps in our understanding of this group of aquatic insects. Aquatic and semi-aquatic moths represent only a tiny fraction of the total lepidopteran diversity. Only about 0.5% of 165 000 known lepidopterans are aquatic; mostly in the preimaginal stages. Truly aquatic species can be found only among the Crambidae, Cosmopterigidae and Erebidae, while semi-aquatic forms associated with amphibious or marsh plants are known in thirteen other families. These lepidopterans have developed various strategies and adaptations that have allowed them to stay under water or in close proximity to water. Problems of respiratory adaptations, locomotor abilities, influence of predators and parasitoids, as well as feeding preferences are discussed. Nevertheless, the poor knowledge on their biology, life cycles, genomics and phylogenetic relationships preclude the generation of fully comprehensive evolutionary scenarios.